One example of a conventional rotary damper is taught in the patent document 1 listed below. The rotary damper includes a damper body having a bottomed circular cylindrical configuration and a rotor, a basal end portion of which is rotatably inserted in the damper body. A first engagement portion including two flat surface portions parallel to each other is formed in a basal end portion of an outer circumferential surface of the damper body, i.e., an end portion of the damper body on a bottom portion side. On the other hand, in a distal end portion of the rotor protruded from the damper body, a second engagement portion including two flat surface portions parallel to each other is formed. A damper mechanism is built-in between the damper body and the rotor. The damper mechanism prohibits the rotor from rotating at a high speed in one direction, maintaining the rotational speed of the rotor at a low speed, and allows the rotor to rotate at a high speed in the other direction.
To mount a rotary damper having the above-described features between a toilet body and a toilet seat, for example, the toilet body may be provided with a first bracket and the toilet seat may be provided with a second bracket. The first bracket includes a first engagement hole. The first engagement portion of the damper body is non-rotatably inserted in the first engagement hole. On the other hand, the second bracket includes a second engagement hole. The second engagement portion of the rotor is non-rotatably inserted in the second engagement hole. By this arrangement, the toilet seat is rotatably connected to the toilet body through the first and second brackets and the rotary damper. When the toilet seat is rotated, the rotor is rotated with respect to the damper body accompanying the rotation of the toilet seat. When the toilet seat is rotated in a closing direction, a rotation speed of the toilet seat is maintained at a low speed by the rotary damper. When the toilet seat is rotated in an opening direction, the rotation speed of the toilet seat is not maintained at a low speed by the rotary damper, and the toilet seat can be rotated at a high speed.